The present invention is directed to an explosive powder charge operated setting device for driving fastening elements, such as studs and nails, into hard receiving materials, such as concrete, steel and the like, where the driving energy is transmitted to the fastening element by a striker piston and the fastening element is equipped with at least one guidance disk.
In so-called direct installation, that is where the fastening elements are driven into the receiving material without any pre-drilling, there are a number of advantages compared to other attachment procedures. For one thing, the installation period is shortened with a corresponding saving in costs. Moreover, loads can be applied directly to the fastening elements.
Direct attachment of fastening elements is quite exacting with regard to the manner in which the direct installation is carried out. The required driving energy varies depending on the type and thickness of the material of the component to be attached and the nature of the receiving material. If the driving energy is too high, the striker piston impacts at the end of the driving operation against the guidance disk resting against the component to be attached. When this occurs, there is a so-called jarring blow which can lead to a loosening of the fastening element driven into the receiving material. Accordingly, the required anchoring values of the fastening elements are not achieved.
The evaluation criteria for the anchored condition of a fastening element is its depth penetration into the receiving material and this can be determined from the degree of deformation of the guidance disk. In the original condition, the guidance disks are not intended to be flat. Making such an evaluation, however, requires considerable experience and specialized knowledge of the user.